EP0109912B1 - Portable hydraulic tools, e.g. hydraulic sécateurs, and process for returning their piston cylinder - Google Patents

Portable hydraulic tools, e.g. hydraulic sécateurs, and process for returning their piston cylinder Download PDF

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Publication number
EP0109912B1
EP0109912B1 EP83430037A EP83430037A EP0109912B1 EP 0109912 B1 EP0109912 B1 EP 0109912B1 EP 83430037 A EP83430037 A EP 83430037A EP 83430037 A EP83430037 A EP 83430037A EP 0109912 B1 EP0109912 B1 EP 0109912B1
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EP
European Patent Office
Prior art keywords
piston
hydraulic
fluid
chamber
return
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83430037A
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German (de)
French (fr)
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EP0109912A1 (en
Inventor
Roger Joseph Pierre Pellenc
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pellenc SAS
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Pellenc et Motte SA
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Publication date
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Priority to AT83430037T priority Critical patent/ATE26901T1/en
Publication of EP0109912A1 publication Critical patent/EP0109912A1/en
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Publication of EP0109912B1 publication Critical patent/EP0109912B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • F15B11/15—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor with special provision for automatic return
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G3/00—Cutting implements specially adapted for horticultural purposes; Delimbing standing trees
    • A01G3/02—Secateurs; Flower or fruit shears
    • A01G3/033—Secateurs; Flower or fruit shears having motor-driven blades
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/5762—With leakage or drip collecting

Definitions

  • An object of the present invention is to remedy the aforementioned drawbacks of known portable hydraulic tools such as, for example, hydraulic shears or shears, comprising a single-acting or double-acting cylinder.
  • this objective is achieved by means of an arrangement and a method according to which the devices are equipped with a single-acting cylinder comprising a piston whose return is ensured by the expansion of a compressible fluid such that, by example, a gaseous fluid, compressed and enclosed in a variable volume return chamber, made watertight, said compressible fluid being subjected to additional compression during the movement of said piston under the pressure of the hydraulic fluid under pressure coming from the hydraulic source under pressure .
  • a compressible fluid such that, by example, a gaseous fluid, compressed and enclosed in a variable volume return chamber, made watertight
  • Another advantage of the arrangement and of the method according to the invention is that they allow a very simple embodiment of the dispenser whose seals do not support any high pressure, so that they are not subjected to any significant force of deformation or extrusion, while a perfect balancing of the movable member of said dispenser is obtained.
  • the tools can operate both in an open center hydraulic circuit and in a closed center hydraulic circuit.
  • Another advantage of the invention lies in the possibility of regulating the return speed of the drive piston and, consequently, the speed of re-opening of the blades, which makes it possible to close them before their complete opening. In the advantageous application to pruning shears, this possibility facilitates pruning or harvesting work, due to the fact that it promotes the penetration of the cutting head of the latter into the vegetation.
  • Figures 1 to 6 illustrate an example of simplified implementation of the invention applied to the production of a hydraulic pruner provided with two movable blades and a body of relatively large length, such a tool more particularly suitable for pruning and the harvesting of palm fruits such as date palms, oil palms, etc.
  • This pruner comprises a body designated as a whole by the reference 1 and composed of a front housing 1a, a rear housing 1b and a tubular extension 1c executed in one or more parts and connecting the rear end of said front housing and the front end of said rear housing.
  • a cutting head comprising a blade holder 2 in the form of a yoke on which two blades 4a, 4b are articulated, by means of an axis 3.
  • the latter comprise, at a distance from the axis 3, a protuberance 4a ', 4b' on which is articulated one of the ends of a pair of rods 5a, 5b also articulated, by its opposite end, on a stem 6 rigidly integral with a plug 7 itself fixed, for example by screwing and sealingly, in the front end of the hollow rod 8 of a drive piston 9.
  • This piston fitted with peripheral seals is housed, with a sealed sliding ability, in the axial recess of the front housing 1a and, more precisely, in a bore 1d formed in the middle portion of the latter.
  • the rod 8 of the piston 9 slides in a sealed manner in a guide 10 positioned, also in a sealed manner, in the front end of the housing before the, this guide provided with peripheral and interior annular seals being held in position by a ring 11 screwed into said front end, and advantageously constituted by the rear end of the blade holder 2.
  • Chamber B communicates with a reservoir chamber C constituted by the axial recess of the piston rod 8, by means of radial holes D made in said rod. Chamber B is thus arranged around chamber C and these two coaxial chambers make it possible to permanently have a large volume available for housing the compressed gaseous fluid, without elongation of the tools, which avoids excessive compression of said gaseous fluid , during the forward movements of the piston 9.
  • the inlet of the chamber C is equipped with a shutter constituted by a valve valve 12a 12a, of a type known per se, and installed in an axial recess of the plug 7 ensuring the sealed closure of said chamber, in its front part.
  • a stop member limits the length of the stroke of the drive piston 9 forward which determines the amplitude of the pivoting of the blades.
  • This abutment member may advantageously be constituted by an openwork sleeve 13 housed in the axial recess of the front housing and arranged around the rod 8, this sleeve being secured, by one of its ends, to the guide 10.
  • a circular shoulder 1st formed in the front housing serves as a stop against which abuts the working face of the piston, at the end of the return stroke.
  • the hydraulic distributor controlling the movements of the piston 9 is installed in a transverse recess 14 which has the rear housing 1b constituting the rear part of the body of the pruning shears.
  • the dispenser comprises a cylindrical jacket 16 provided with two large peripheral annular grooves I, J.
  • the groove 1 communicates permanently with the feed orifice E and with the channel G. It also communicates with the bore of the jacket 16, by means of radial holes K made in the latter.
  • the groove J constantly communicates with the return F and, depending on the position of the distribution slide described below, with the bore of the jacket 16, on the one hand, thanks to radial holes L and. on the other hand, by means of radial holes M of smaller diameter and arranged in front of said radial holes, relative to the internal end of said jacket.
  • the movable member of the dispenser which is advantageously executed in one piece and comprises a dispensing drawer 17 delimiting, inside said bore, two annular chambers N, O.
  • the distribution chamber N is in constant communication with the inlet E, by the passage KI, and with the channel G, also by the passage KI, the said chamber therefore also communicating permanently with the chamber A delimited by the working face of the drive piston 9.
  • the chamber N is also delimited by a balance piston 18 constituting the internal end of the movable member of the dispenser. This balance piston has two peripheral grooves 18a, 18b.
  • the groove 18a closest to its outer end is housed an annular seal 19, while the groove 18b closest to the chamber N communicates with a channel P formed axially inside the rod 20 of said movable member, via at least one radial hole Q.
  • the channel P communicates with the chamber 0, via at least one radial orifice R, said chamber being constantly in relation to the return F, through the passage MJ.
  • the evacuation chamber 0 is also delimited by a cylindrical obturator 21 constituted by a circular boss presented by the rod 20 in the vicinity of its external portion and comprising a peripheral groove 21a in which is housed an annular seal 22.
  • the cylindrical shutter 21 In the rest position, the cylindrical shutter 21 is in abutment against a stop washer 23a immobilized by a circlip 23 installed in a circular groove formed at the inlet of the jacket 16 from which the external end 24 forming trigger of the rod 20.
  • the latter is subjected to the action of a compression spring 25 placed in abutment, by its opposite ends, on the one hand, against the bottom of a blind housing 26 formed in the bottom of said rod and, on the other hand, against the bottom of a plug 27 screwed into the threaded end of the recess 14 opposite the end from which the trigger 24 emerges, said spring tending to push the latter into the emerging position .
  • the operating lever 28 of the pruner is articulated, bearing against the trigger 24 and whose pivoting inwards makes it possible to repel the latter against the antagonistic action exerted by the spring 25.
  • a compressible fluid is introduced and compressed in the coaxial chambers C and B, which has the effect of pushing the piston 9 backwards and keeping it wedged against the shoulder 1e.
  • the compressible fluid which can be used is advantageously a gaseous fluid, for example compressed air or, preferably, a compressed neutral gas which does not dissolve little or not in oil such as nitrogen, argon, etc.
  • this oil is collected in the groove 18b and, via the passage QPR-0-MJ, it is conveyed until the return F
  • the seal 19 fitted to the balance piston therefore does not withstand any pressure.
  • the seal 22 which is fitted with the cylindrical shutter 21 is not subjected to any pressure, since the chamber 0 delimited by said shutter communicates permanently with the return.
  • the recoil speed of the piston and therefore the speed of pivoting of the blades in the open position are linked to the value of the compression of the compressed gas contained in chambers B and C. It is understood that, by the choice of the compression ratio of this gas, it is possible to easily and conveniently adjust the speed of the reopening of the blades.
  • FIG. 7 illustrates a very advantageous arrangement of the cutting head of the pruning shears.
  • a ball stop 29a, 29b is installed on the axis 3, on each side of the pair of blades 4a, 4b, between the branches 2a, 2b of the yoke constituting the front portion of the blade holder 2.
  • the axis 3 is constituted by a bolt making it possible to keep the blades 4a, 4b in contact with one another. So that the pressure tending to press said blades against each other is always sufficient to obtain a clean cut, without however counteracting the pivoting of the movable blade or blades, this pressure is applied to the pair of blades by means of 'an elastic organ.
  • this elastic member is constituted by a Belleville washer 30, for example interposed between the internal face of the nut 3a of the bolt 3 and a ring 59 mounted with an ability of axial translation on the rod of said bolt, in a housing 2b ′ of one of the branches (branch 2b) of the blade holder, this movable ring being itself interposed between said Belleville washer and one of the ball thrust bearings (ball thrust 29b).
  • FIGS 9 to 13 illustrate a second example of implementation of the invention applied to the production of another type of hydraulic pruner suitable for conventional pruning and harvesting work in arboriculture, viticulture and horticulture.
  • This pruner includes a hollow body 31, the rear portion of which is shaped to serve as a handle and on the front part of which is installed a cutting head comprising a blade holder 32 on which is fixed a hook or fixed blade 33. On this hook, is articulated, by means of an axis 34, the movable blade 35 of said cutting head.
  • This movable blade has an extension or lever 35a having an open slot 36 crossed by a driving slide 37 carried by the front end in the form of a yoke 58a of a plug 58 installed in leaktight manner in the front end of a reamed rod 38.
  • the drive slide 37 slides in the slot 36.
  • This arrangement facilitates the connection of the movable blade and the rod. by eliminating the use of an intermediate organ.
  • the face of work of this piston delimits a chamber a of variable volume, while its opposite face delimits an annular chamber of variable volume b surrounding the rod 38.
  • the latter can slide, in a sealed manner, in a guide 40 fixed, preferably so removable, in the front part of the recess of the body 31, this guide being provided, internally and externally, with annular seals.
  • a free piston 41 fitted with peripheral annular seals.
  • This free piston delimits, inside said bore, on the one hand, by its front face, a chamber c and, on the other hand, by its rear face, a second chamber from which constantly communicates with the annular chamber b, by means of at least one orifice e formed in the cylindrical wall of the rod 38.
  • the concentric chambers b and d constitute, with the orifice e making them communicate, a chamber with variable capacity intended to contain an incompressible fluid of transmission, as explained below.
  • a valve 42 is installed at the front of the rod 38, in an axial recess of the plug 58, at the entrance to the chamber c, this valve making it possible to introduce a compressible fluid such as air, nitrogen, argon, etc. ., in said chamber sealed by means of said plug.
  • the rear end of the rod 38 has an axial bore f arranged in alignment with an axial orifice g formed in the piston 39 and communicating with the chamber a.
  • a non-return valve 43 and a compression spring 44 tending to hold said valve against the front edge of the orifice g.
  • open two radial holes h opening in the lateral surface of a frustoconical portion 38c which has the rod 38 in front of its cylindrical rear end of reduced diameter engaged in the piston 39, that is to say - say in the immediate vicinity and in front of the latter.
  • This conical surface serves as a seat for an annular valve 45 having a complementary conical bearing surface.
  • This valve 45 is provided with peripheral grooves 45a oriented parallel to its axis, and it is held on its seat by an elastic means advantageously constituted by a Belleville washer 46 interposed between its rear face and the front face of the piston 39.
  • a stop ring 47 having a double function: - on the one hand. limit the stroke of piston 39 towards the front and. - on the other hand. lift the valve 45 from its seat when said piston reaches the end of the travel stroke.
  • a purge orifice 48 communicating with the anterior end of the annular chamber b. is provided in the body 31, this orifice being equipped with a sealed closure member.
  • the rear end of the body 31 is arranged to receive a device (not shown) allowing the demountable, convenient and rapid coupling of the pruning shears to coaxial supply and return hoses connected to a source of hydraulic fluid under pressure, such a removable coupling device being described in document FR-A-2419453.
  • the distributor comprises a cylindrical jacket 50 fixedly installed in the recess 49, a mobile distribution member mounted with a sliding ability in the axial bore of said jacket, and a compression spring 51 interposed between the bottom of said recess and the bottom an axial cavity formed in the internal portion of said member.
  • the cylindrical jacket 50 has two peripheral annular grooves I, m.
  • the groove I communicates permanently with the inlet j, and also with the bore q of the liner by means of radial holes n, the inlet of which is placed in the rear part of the said groove, relative to the end. external of said shirt.
  • the groove m communicates directly with the conduit i, and also with the bore q of the jacket, by means of radial holes o arranged behind the holes n.
  • the movable member of the dispenser is advantageously executed in a single piece and comprises a dispensing slide 52 defining, with a balance piston 53, an annular chamber p which is in constant relation with the inlet j, through the passage n-I.
  • Said movable member also comprises a trigger or pusher 54 constituted by one of its ends emerging from the inlet of the liner, and it is held inside the latter by means of a stop washer 55 immobilized by a circlip 56 positioned in an internal circular groove formed near the inlet of said jacket and against which the external face of the balance piston bears, under the thrust of the spring 51.
  • the pruning shears are first prepared to work.
  • the chamber c is filled with a compressed gaseous fluid, via the valve 42 and with the aid of any suitable material, which has the effect of maintaining or pushing the free piston 41 in the bottom of the bore of the piston rod 38, the bleed orifice 48 being open for the evacuation of the air located in the chamber d.
  • the pruning shears being connected to the source of pressurized hydraulic fluid, the pressurized hydraulic fluid such as oil is then sent, by acting on the distributor, against the working face of the drive piston 39 which is pushed towards the before at the same time as the rod 38 and the valve 45 disposed at the front of said piston.
  • the stop 47 causes the valve 45 to be raised.
  • the non-return valve 43 Given the opening of the radial bores h, the non-return valve 43 is detached from its seat and the oil enters the chambers b and d which have their minimum volume. These chambers are filled with oil which expels the air therein. When the oil comes out of the bleed orifice 48, the latter is closed using its sealed shutter. The pressure which is then created in the chambers b and da has the effect of pushing the free piston 41 forwards, by increasing the volume of the chamber d and by subjecting the compressed gas contained in the chamber c, the volume of which decreases, to additional compression.
  • the chamber a communicates with the return by the passage i-m-o-q and the bottom of the recess 49.
  • the valve 45 is raised from its seat, against the antagonistic action of the Belleville washer 46, when it meets the stop 47.
  • very slight oil leaks inevitable in all cylinder system are automatically compensated by the entry into chambers b and d of a corresponding amount of oil from chamber a through the passage gfh.
  • the pressure exerted on the rear face of the non-return valve 43 makes it possible to take it off from its seat when the valve 45 is lifted from its own, this which allows the entry of a compensating quantity of oil into said chambers, until the pressures balance in said chambers and in chamber c. In this way, the volume of oil contained in the chambers b and d is always constant.
  • This simplified and economical embodiment differs from that illustrated in FIGS. 1 to 8, mainly by the fact that the return chamber B containing or capable of enclosing the compressed gaseous fluid, is delimited by the large face of the piston.
  • drive 9 and is arranged in the rear part of the front housing 1a, while the hydraulic pressure chamber A is delimited by the small working face of said piston and disposed around the rod 8, in the front part of said housing.
  • the valve 12 making it possible to introduce the compressed gaseous fluid into the return chamber B is therefore installed in a housing provided in the rear part of the housing 1a and opening into said chamber, while the orifice H ′ of inlet of the hydraulic fluid in the pressure chamber A is executed in the front part of said housing.

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Abstract

A portable hydraulic tool, such as a hydraulic secateurs, is of the kind having a single acting ram including a driving piston with its piston rod connected to at least one movable operating member such as a cutting element of the tool, the piston being movable in fluid tight manner in a bore under the thrust of hydraulic fluid acting on a working face of the piston, the improvement being that there is provided a return chamber the volume of which decreases when the driving piston is displaced in its working stroke, the return chamber containing a compressible fluid under pressure such that, when the thrust exerted on the piston by the hydraulic fluid becomes less than the thrust exerted on the piston by the compressible fluid, the piston is caused to carry out a return stroke by the expansion of the compressible fluid.

Description

La présente invention concerne les outils hydrauliques portatifs tels que, par exemple, les sécateurs ou cisailles hydrauliques comportant un corps évidé à l'avant duquel sont installées deux lames dont au moins une lame pivotante actionnée par un dispositif hydraulique comprenant : d'une part, un vérin à simple effet comportant un piston d'entraînement dont la tige est assujettie à ladite lame pivotante et, d'autre part, un distributeur hydraulique permettant d'envoyer le fluide hydraulique sous pression contre la face de travail dudit piston afin d'en assurer le déplacement dans le sens correspondant à la fermeture des lames. L'invention concerne également le procédé de rappel du piston du vérin desdits outils hydrauliques portatifs. Les outils hydrauliques portatifs connus, par exemple les sécateurs hydrauliques comprennent généralement un vérin à simple effet ou un vérin à double effet. Dans le premier cas (FR-A-2 336 072), le fluide hydraulique sous pression provenant d'une source de fluide hydraulique sous pression (pompe, circuit hydraulique d'un tracteur, d'une plateforme automotrice ou autres véhicules, groupe hydraulique adaptable sur motoculteur, groupe hydro-électrique, etc.) est appliqué sur une seule face ou face de travail du piston du vérin dont le retour est assuré au moyen d'un ressort de compression logé dans une chambre de rappel de volume variable lequel décroît lorsque le piston d'entraînement se déplace sous la poussée du fluide hydraulique sous pression permettant ainsi de comprimer ledit ressort dont la détente provoque ainsi le retour dudit piston. La présence de ce dernier engendre un certain nombre d'inconvénients parmi lesquels on souligne notamment :

  • un retour du piston à vitesse non régiabie ;
  • une cassure fréquente de ce ressort ;
  • une augmentation du diamètre des appareils due à la nécessité de prévoir une chambre annulaire de dimension radiale importante entre la périphérie de la tige du piston et la paroi de l'alésage dans lequel sont montés ce dernier et ladite tige ;
  • un alourdissement des appareils.
The present invention relates to portable hydraulic tools such as, for example, hydraulic shears or shears comprising a hollow body at the front of which are installed two blades, at least one pivoting blade of which is actuated by a hydraulic device comprising: on the one hand, a single-acting cylinder comprising a drive piston whose rod is subject to said pivoting blade and, on the other hand, a hydraulic distributor making it possible to send the hydraulic fluid under pressure against the working face of said piston in order to move in the direction corresponding to the closing of the blades. The invention also relates to the method of returning the piston of the jack of said portable hydraulic tools. Known portable hydraulic tools, for example hydraulic secateurs generally comprise a single-acting cylinder or a double-acting cylinder. In the first case (FR-A-2 336 072), the hydraulic fluid under pressure coming from a source of hydraulic fluid under pressure (pump, hydraulic circuit of a tractor, of a self-propelled platform or other vehicles, hydraulic group adaptable to tiller, hydroelectric group, etc.) is applied to a single face or working face of the cylinder piston, the return of which is ensured by means of a compression spring housed in a return chamber of variable volume which decreases when the drive piston moves under the pressure of the hydraulic fluid under pressure, thus making it possible to compress said spring, the relaxation of which thus causes said piston to return. The presence of the latter generates a certain number of drawbacks, among which it is notably emphasized:
  • a return of the piston at non-controllable speed;
  • frequent breakage of this spring;
  • an increase in the diameter of the devices due to the need to provide an annular chamber of large radial dimension between the periphery of the piston rod and the wall of the bore in which the latter and said rod are mounted;
  • an increase in the weight of the devices.

En raison de ces inconvénients, on préfère souvent équiper les outils hydrauliques avec un vérin à double effet dont le piston comporte deux faces de travail opposées, ou avec un vérin différentiel dont le piston comporte également deux faces de travail opposées de surfaces inégales (FR-A-2 367 422). Toutefois, dans ce cas, la construction des appareils se trouve compliquée par la nécessité de prévoir deux conduits distincts pour amener le fluide hydraulique sous pression provenant de la source de fluide hydraulique sous pression alternativement contre l'une ou l'autre desdites faces de travail, ainsi qu'un distributeur à double effet relativement complexe pour régler la circulation de l'huile dans ces conduits et en direction du retour. D'autre part. la quantité d'huile utilisée pour chaque course aller-retour du piston, est nettement supérieure à celle qui est demandée par un vérin à simple effet, ce qui engendre une baisse du rendement du sécateur ou autre outil hydraulique. En outre, les outils équipés d'un vérin différentiel ne peuvent fonctionner qu'en circuit hydraulique à centre fermé. Enfin, cet agencement complexe des outils conduit aussi à un dimensionnement important et à un alourdissement de ces derniers qui, dans le cas des sécateurs destinés aux travaux agricoles de taille ou de récolte, influent de manière défavorable sur leur maniabilité et sur la précision desdits travaux et sont, en outre, des facteurs de fatigue des utilisateurs.Because of these drawbacks, it is often preferred to equip hydraulic tools with a double-acting cylinder whose piston has two opposite working faces, or with a differential cylinder whose piston also has two opposite working faces with uneven surfaces (FR- A-2 367 422). However, in this case, the construction of the apparatuses is complicated by the need to provide two separate conduits for bringing the hydraulic fluid under pressure coming from the source of hydraulic fluid under pressure alternately against one or the other of said working faces. , as well as a relatively complex double-acting distributor for regulating the circulation of oil in these conduits and towards the return. On the other hand. the quantity of oil used for each return stroke of the piston is much higher than that required by a single-acting cylinder, which results in a reduction in the yield of the pruning shears or other hydraulic tool. In addition, tools fitted with a differential cylinder can only operate in a closed center hydraulic circuit. Finally, this complex arrangement of tools also leads to significant sizing and weighing down of the latter which, in the case of pruners intended for pruning or harvesting agricultural work, adversely affect their maneuverability and the precision of said work. and are, moreover, factors of user fatigue.

Un but visé par la présente invention est de remédier aux inconvénients susmentionnés des outils hydrauliques portatifs connus tels que, par exemple, les sécateurs ou cisailles hydrauliques, comportant un vérin à simple effet ou à double effet.An object of the present invention is to remedy the aforementioned drawbacks of known portable hydraulic tools such as, for example, hydraulic shears or shears, comprising a single-acting or double-acting cylinder.

Selon l'invention, cet objectif est atteint grâce à un agencement et à un procédé suivant lesquels les appareils sont équipés d'un vérin à simple effet comprenant un piston dont le rappel est assuré par la détente d'un fluide compressible tel que, par exemple, un fluide gazeux, comprimé et renfermé dans une chambre de rappel à volume variable, rendue étanche, ledit fluide compressible étant soumis à une compression supplémentaire lors du déplacement dudit piston sous la poussée du fluide hydraulique sous pression provenant de la source hydraulique sous pression.According to the invention, this objective is achieved by means of an arrangement and a method according to which the devices are equipped with a single-acting cylinder comprising a piston whose return is ensured by the expansion of a compressible fluid such that, by example, a gaseous fluid, compressed and enclosed in a variable volume return chamber, made watertight, said compressible fluid being subjected to additional compression during the movement of said piston under the pressure of the hydraulic fluid under pressure coming from the hydraulic source under pressure .

Cet agencement et ce procédé permettent la réalisation d'appareils et d'outils hydrauliques portatifs divers tels que, par exemple, des sécateurs hydrauliques, d'une grande simplicité constructive découlant notamment de la possibilité d'utiliser un distributeur à simple effet et de la présence d'un seul conduit reliant ce distributeur à la chambre délimitée par la face de travail du piston d'entraînement. Cette grande simplicité a pour corollaire un fonctionnement sûr et durable des appareils ou outils. D'autre part, ces derniers peuvent être exécutés avec des diamètres réduits et une légèreté accrue par rapport aux appareils et outils du même genre connus. Un autre avantage de l'agencement et du procédé selon l'invention est qu'ils autorisent une réalisation très simple du distributeur dont les joints d'étanchéité ne supportent aucune pression élevée, de sorte qu'ils ne sont soumis à aucune force importante de déformation ou d'extrusion, tandis que l'on obtient un équilibrage parfait de l'organe mobile dudit distributeur. D'autre part, les outils peuvent fonctionner aussi bien en circuit hydraulique à centre ouvert qu'en circuit hydraulique à centre fermé. Un autre avantage de l'invention réside dans la possibilité de régler la vitesse de retour du piston d'entraînement et, par conséquent, la vitesse de ré-ouverture des lames, ce qui permet de les refermer avant leur complète ouverture. Dans l'application avantageuse aux sécateurs, cette possibilité facilite le travail de taille ou de récolte, en raison du fait qu'elle favorise la pénétration de la tête de coupe de ces derniers dans la végétation.This arrangement and this process allow the production of various portable hydraulic devices and tools such as, for example, hydraulic secateurs, of great constructive simplicity arising in particular from the possibility of using a single-acting distributor and the presence of a single conduit connecting this distributor to the chamber delimited by the working face of the drive piston. This great simplicity has for corollary a safe and durable functioning of the apparatuses or tools. On the other hand, the latter can be executed with reduced diameters and an increased lightness compared to known devices and tools of the same kind. Another advantage of the arrangement and of the method according to the invention is that they allow a very simple embodiment of the dispenser whose seals do not support any high pressure, so that they are not subjected to any significant force of deformation or extrusion, while a perfect balancing of the movable member of said dispenser is obtained. On the other hand, the tools can operate both in an open center hydraulic circuit and in a closed center hydraulic circuit. Another advantage of the invention lies in the possibility of regulating the return speed of the drive piston and, consequently, the speed of re-opening of the blades, which makes it possible to close them before their complete opening. In the advantageous application to pruning shears, this possibility facilitates pruning or harvesting work, due to the fact that it promotes the penetration of the cutting head of the latter into the vegetation.

Ces buts, caractéristiques et avantages, et d'autres encore, ressortiront mieux de la description qui suit et des dessins annexés dans lesquels :

  • La figure 1 est une vue partielle, en coupe axiale, d'un premier exemple d'exécution d'un sécateur hydraulique réalisé selon l'invention, dont les différents organes mobiles sont représentés dans une position correspondant à l'ouverture des lames.
  • La figure 2 est une vue partielle, en coupe axiale, de la partie avant équipée de la tête de coupe de ce sécateur.
  • Les figures 3 et 4 sont des vues partielles, en coupe axiale et à plus grande échelle, de la partie avant équipée du vérin à simple effet et de la partie arrière dans laquelle est installé le distributeur hydraulique, respectivement, représentées dans des positions correspondant à l'ouverture des lames.
  • Les figures 5 et 6 sont des vues analogues aux figures 3 et 4, respectivement, illustrant lesdites parties avant et arrière dans des positions correspondant à la fermeture des lames.
  • La figure 7 est une vue de face, avec coupe partielle, de la tête de coupe perfectionnée de ce sécateur.
  • La figure 8 est, à plus grande échelle, une vue en coupe axiale du distributeur hydraulique à simple effet dudit sécateur.
  • La figure 9 est une vue en coupe axiale d'un autre mode d'exécution d'un sécateur hydraulique réalisé selon l'invention, dont les lames n'ont été représentées que partiellement et dont les différents organes mobiles sont illustrés dans des positions correspondant à l'ouverture desdites lames.
  • Les figures 10 et 11 sont des vues partielles, en coupe axiale et à plus grande échelle, de la partie avant équipée du vérin à simple effet et de la partie arrière dans laquelle est installé le distributeur hydraulique, respectivement, représentées dans la position d'ouverture des lames.
  • Les figures 12 et 13 sont des vues analogues aux figures 10 et 11, respectivement, illustrant lesdites parties avant et arrière dans des positions correspondant à la fermeture des lames.
  • La figure 14 est une vue en coupe axiale d'un autre mode d'exécution d'un sécateur hyraulique analogue à celui qui est illustré aux figures 1 à 8 et dont seul l'outil de coupe proprement dit est représenté, les différents organes mobiles de cet outil étant montrés dans des positions correspondant à la fermeture de ses lames de coupe.
  • La figure 15 est une vue en coupe axiale de cet outil de coupe dont les organes mobiles sont montrés dans des positions correspondant à l'ouverture de ses lames.
  • La figure 16 est une vue partielle, en coupe axiale et à plus grande échelle de la figure 14.
These aims, characteristics and advantages, and others still, will emerge more clearly from the description which follows and from the appended drawings in which:
  • Figure 1 is a partial view, in axial section, of a first embodiment of a hydraulic pruner produced according to the invention, the various movable members of which are shown in a position corresponding to the opening of the blades.
  • Figure 2 is a partial view, in axial section, of the front part equipped with the cutting head of this pruner.
  • Figures 3 and 4 are partial views, in axial section and on a larger scale, of the front part equipped with the single-acting cylinder and of the rear part in which the hydraulic distributor is installed, respectively, represented in positions corresponding to opening the blades.
  • Figures 5 and 6 are views similar to Figures 3 and 4, respectively, illustrating said front and rear parts in positions corresponding to the closing of the blades.
  • Figure 7 is a front view, partly in section, of the improved cutting head of this pruning shears.
  • Figure 8 is, on a larger scale, an axial sectional view of the single-acting hydraulic distributor of said pruning shears.
  • FIG. 9 is a view in axial section of another embodiment of a hydraulic pruning shears produced according to the invention, the blades of which have only been shown partially and the different movable members of which are illustrated in corresponding positions when said blades open.
  • FIGS. 10 and 11 are partial views, in axial section and on a larger scale, of the front part equipped with the single-acting cylinder and of the rear part in which the hydraulic distributor is installed, respectively, represented in the position of blade opening.
  • Figures 12 and 13 are views similar to Figures 10 and 11, respectively, illustrating said front and rear portions in positions corresponding to the closing of the blades.
  • Figure 14 is an axial sectional view of another embodiment of a hydraulic pruner similar to that which is illustrated in Figures 1 to 8 and of which only the cutting tool itself is shown, the various movable members of this tool being shown in positions corresponding to the closing of its cutting blades.
  • Figure 15 is an axial sectional view of this cutting tool whose movable members are shown in positions corresponding to the opening of its blades.
  • FIG. 16 is a partial view, in axial section and on a larger scale of FIG. 14.

On se réfère auxdits dessins pour décrire des exemples intéressants, quoique nullement limitatifs, de mise en oeuvre du procédé et de réalisation des outils portatifs hydrauliques selon l'invention.Reference is made to said drawings to describe interesting examples, although in no way limitative, of implementation of the method and production of the portable hydraulic tools according to the invention.

On se reporte, dans l'exposé qui suit, à une application particulièrement intéressante de l'invention à la réalisation de sécateurs hydrauliques utilisables pour travaux de taille ou de récolte, en agriculture, arboriculture, viticulture ou horticulture. Toutefois, on souligne que l'invention peut être appliquée à la réalisation d'appareils ou outils hydrauliques portatifs divers, tels que, par exemple, cisailles pour découper les tôles des caisses de véhicules accidentés, pinces de serrage hydrauliques, etc.Reference is made, in the following description, to a particularly advantageous application of the invention to the production of hydraulic shears used for pruning or harvesting, in agriculture, arboriculture, viticulture or horticulture. However, it is emphasized that the invention can be applied to the production of various portable hydraulic devices or tools, such as, for example, shears for cutting the sheets of the bodies of damaged vehicles, hydraulic collets, etc.

Les figures 1 à 6 illustrent un exemple de mise en oeuvre simplifiée de l'invention appliquée à la réalisation d'un sécateur hydraulique pourvu de deux lames mobiles et d'un corps de longueur relativement importante, un tel outil convenant plus particulièrement à la taille et à la récolte des fruits des palmiers tels que palmiers-dattiers, palmiers à huile, etc.Figures 1 to 6 illustrate an example of simplified implementation of the invention applied to the production of a hydraulic pruner provided with two movable blades and a body of relatively large length, such a tool more particularly suitable for pruning and the harvesting of palm fruits such as date palms, oil palms, etc.

Ce sécateur comprend un corps désigné dans son ensemble par la référence 1 et composé d'un boîtier avant 1a, d'un boîtier arrière 1b et d'une allonge tubulaire 1c exécutée en une ou plusieurs parties et reliant l'extrémité postérieure dudit boîtier avant et l'extrémité antérieure dudit boîtier arrière.This pruner comprises a body designated as a whole by the reference 1 and composed of a front housing 1a, a rear housing 1b and a tubular extension 1c executed in one or more parts and connecting the rear end of said front housing and the front end of said rear housing.

Sur l'extrémité antérieure du boîtier avant, est installée une tête de coupe comportant un porte-lames 2 en forme de chape sur lequel sont articulées, au moyen d'un axe 3, deux lames 4a, 4b. Ces dernières comportent, à distance de l'axe 3, une protubérance 4a', 4b' sur laquelle est articulée l'une des extrémités d'un couple de biellettes 5a, 5b également articulé, par son extrémité opposée, sur une potence 6 rigidement solidaire d'un bouchon 7 lui-même fixé, par exemple par vissage et de manière étanche, dans l'extrémité avant de la tige creuse 8 d'un piston d'entraînement 9. Ce piston équipé de joints périphériques d'étanchéité, est logé, avec une aptitude de coulissement étanche, dans l'évidement axial du boîtier avant 1a et, plus précisément, dans un alésage 1d formé dans la portion médiane de ce dernier. La tige 8 du piston 9 coulisse, de manière étanche, dans un guide 10 positionné, également de façon étanche, dans l'extrémité antérieure du boîtier avant la, ce guide muni de joints d'étanchéité annulaires périphériques et intérieurs étant maintenu en position par une bague 11 vissée dans ladite extrémité antérieure, et avantageusement constituée par l'extrémité postérieure du porte-lame 2.On the front end of the front housing, a cutting head is installed comprising a blade holder 2 in the form of a yoke on which two blades 4a, 4b are articulated, by means of an axis 3. The latter comprise, at a distance from the axis 3, a protuberance 4a ', 4b' on which is articulated one of the ends of a pair of rods 5a, 5b also articulated, by its opposite end, on a stem 6 rigidly integral with a plug 7 itself fixed, for example by screwing and sealingly, in the front end of the hollow rod 8 of a drive piston 9. This piston fitted with peripheral seals, is housed, with a sealed sliding ability, in the axial recess of the front housing 1a and, more precisely, in a bore 1d formed in the middle portion of the latter. The rod 8 of the piston 9 slides in a sealed manner in a guide 10 positioned, also in a sealed manner, in the front end of the housing before the, this guide provided with peripheral and interior annular seals being held in position by a ring 11 screwed into said front end, and advantageously constituted by the rear end of the blade holder 2.

Le piston 9 délimite, par ses faces opposées :

  • d'une part, une chambre A communiquant en permanence avec l'arrivée du fluide hydraulique provenant de la source de fluide hydraulique et susceptible d'être mise en relation avec le retour dudit fluide ;
  • d'une part, une chambre annulaire de rappel B de volume variable. renfermant ou apte à renfermer un fluide compressible comprimé et, de préférence, un fluide gazeux comprimé, en entourant la tige de piston 8, cette chambre étant rendue étanche au moyen du guide 10.
The piston 9 delimits, by its opposite faces:
  • on the one hand, a chamber A permanently communicating with the arrival of the hydraulic fluid coming from the source of hydraulic fluid and capable of being connected with the return of said fluid;
  • on the one hand, an annular return chamber B of variable volume. containing or capable of enclosing a compressed compressible fluid and, preferably, a compressed gaseous fluid, surrounding the piston rod 8, this chamber being sealed by means of the guide 10.

La chambre B communique avec une chambre- réservoir C constituée par l'évidement axial de la tige de piston 8, par l'intermédiaire de trous radiaux D ménagés dans ladite tige. La chambre B est ainsi disposée autour de la chambre C et ces deux chambres coaxiales permettent de disposer en permanence d'un important volume disponible pour le logement du fluide gazeux comprimé, sans allongement des outils, ce qui évite une compression trop importante dudit fluide gazeux, lors des mouvements d'avance du piston 9. L'entrée de la chambre C est équipée d'un obturateur constitué par une valve 12 à clapet 12a, de type connu en soi, et installée dans un évidement axial du bouchon 7 assurant la fermeture étanche de ladite chambre, dans sa partie avant. Un organe de butée limite la longueur de la course du piston d'entraînement 9 vers l'avant laquelle détermine l'amplitude du pivotement des lames. Cet organe de butée peut être avantageusement constitué par un manchon ajouré 13 logé dans l'évidement axial du boîtier avant et disposé autour de la tige 8, ce manchon étant solidaire, par l'une de ses extrémités, du guide 10. Un épaulement circulaire 1e ménagé dans le boîtier avant sert de butée contre laquelle vient en appui la face de travail du piston, en fin de course de retour.Chamber B communicates with a reservoir chamber C constituted by the axial recess of the piston rod 8, by means of radial holes D made in said rod. Chamber B is thus arranged around chamber C and these two coaxial chambers make it possible to permanently have a large volume available for housing the compressed gaseous fluid, without elongation of the tools, which avoids excessive compression of said gaseous fluid , during the forward movements of the piston 9. The inlet of the chamber C is equipped with a shutter constituted by a valve valve 12a 12a, of a type known per se, and installed in an axial recess of the plug 7 ensuring the sealed closure of said chamber, in its front part. A stop member limits the length of the stroke of the drive piston 9 forward which determines the amplitude of the pivoting of the blades. This abutment member may advantageously be constituted by an openwork sleeve 13 housed in the axial recess of the front housing and arranged around the rod 8, this sleeve being secured, by one of its ends, to the guide 10. A circular shoulder 1st formed in the front housing serves as a stop against which abuts the working face of the piston, at the end of the return stroke.

Le distributeur hydraulique commandant les déplacements du piston 9 est installé dans un évidement transversal 14 que présente le boîtier arrière 1b constituant la partie postérieure du corps du sécateur.The hydraulic distributor controlling the movements of the piston 9 is installed in a transverse recess 14 which has the rear housing 1b constituting the rear part of the body of the pruning shears.

Dans cet évidement d'axe perpendiculaire à l'axe du piston 9, débouchent :

  • l'orifice d'alimentation ou arrivée du fluide E ménagé à la partie postérieure du boîtier arrière 1 b et agencé pour pouvoir être raccordé, de toute manière connue, à une tuyauterie souple (non représentée) elle-même reliée à une source de fluide hydraulique ;
  • l'orifice de retour F, par exemple disposé au-dessous du précédent et également agencé pour pouvoir être raccordé à une tuyauterie souple de retour (non illustrée) ;
    • un canal longitudinal G communiquant avec la chambre A délimitée par la face de travail du piston 9 ; ce canal longitudinal est, suivant le mode d'exécution illustré, constitué par un perçage ménagé dans le boîtier arrière 1b et par un tuyau de jonction 15 rigide ou souple, reliant, de manière étanche, l'extrémité avant dudit perçage et un orifice H dont est pourvue la portion postérieure du boîtier avant 1a et débouchant dans la chambre A.
In this recess with an axis perpendicular to the axis of the piston 9, open:
  • the fluid supply or inlet orifice E formed in the rear part of the rear housing 1b and arranged to be able to be connected, in any known manner, to a flexible pipe (not shown) itself connected to a source of fluid hydraulic;
  • the return orifice F, for example arranged below the previous one and also arranged to be able to be connected to a flexible return pipe (not illustrated);
    • a longitudinal channel G communicating with the chamber A delimited by the working face of the piston 9; according to the illustrated embodiment, this longitudinal channel is constituted by a bore formed in the rear housing 1b and by a rigid or flexible junction pipe 15, sealingly connecting the front end of said bore and an orifice H which is provided with the rear portion of the front housing 1a and opening into the chamber A.

Le distributeur comprend une chemise cylindrique 16 dotée de deux larges gorges annulaires périphériques I, J.The dispenser comprises a cylindrical jacket 16 provided with two large peripheral annular grooves I, J.

La gorge 1 communique en permanence avec l'orifice d'alimentation E et avec le canal G. Elle communique également avec l'alésage de la chemise 16, par l'intermédiaire de trous radiaux K ménagés dans cette dernière.The groove 1 communicates permanently with the feed orifice E and with the channel G. It also communicates with the bore of the jacket 16, by means of radial holes K made in the latter.

La gorge J communique constamment avec le retour F et, suivant la position du tiroir de distribution décrit ci-après, avec l'alésage de la chemise 16, d'une part, grâce à des trous radiaux L et. d'autre part, par l'intermédiaire d'orifices radiaux M de diamètre plus réduit et disposés en avant desdits trous radiaux, par rapport à l'extrémité interne de ladite chemise.The groove J constantly communicates with the return F and, depending on the position of the distribution slide described below, with the bore of the jacket 16, on the one hand, thanks to radial holes L and. on the other hand, by means of radial holes M of smaller diameter and arranged in front of said radial holes, relative to the internal end of said jacket.

Dans l'alésage de la chemise 16 est monté, avec une latitude de coulissement, l'organe mobile du distributeur lequel est avantageusement exécuté en une seule pièce et comprend un tiroir de distribution 17 délimitant, à l'intérieur dudit alésage, deux chambres annulaires N, O. La chambre de distribution N est en communication constante avec l'arrivée E, par le passage K-I, et avec le canal G, également par le passage K-I, ladite chambre communiquant donc aussi en permanence avec la chambre A délimitée par la face de travail du piston d'entraînement 9. Suivant la position du tiroir de distribution 17, elle communique ou non avec le retour F, par le passage L-J. La chambre N est également délimitée par un piston d'équilibre 18 constituant l'extrémité interne de l'organe mobile du distributeur. Ce piston d'équilibre comporte deux gorges périphériques 18a, 18b. Dans la gorge 18a la plus proche de son extrémité externe, est logé un joint d'étanchéité annulaire 19, tandis que la gorge 18b la plus proche de la chambre N communique avec un canal P ménagé axialement à l'intérieur de la tige 20 dudit organe mobile, par l'intermédiaire d'au moins un trou radial Q. D'autre part, le canal P communique avec la chambre 0, par l'intermédiaire d'au moins un orifice radial R, ladite chambre étant constamment en relation avec le retour F, par le passage M-J.In the bore of the jacket 16 is mounted, with a sliding latitude, the movable member of the dispenser which is advantageously executed in one piece and comprises a dispensing drawer 17 delimiting, inside said bore, two annular chambers N, O. The distribution chamber N is in constant communication with the inlet E, by the passage KI, and with the channel G, also by the passage KI, the said chamber therefore also communicating permanently with the chamber A delimited by the working face of the drive piston 9. Depending on the position of the distribution slide 17, it may or may not communicate with the return F, through the passage LJ. The chamber N is also delimited by a balance piston 18 constituting the internal end of the movable member of the dispenser. This balance piston has two peripheral grooves 18a, 18b. In the groove 18a closest to its outer end, is housed an annular seal 19, while the groove 18b closest to the chamber N communicates with a channel P formed axially inside the rod 20 of said movable member, via at least one radial hole Q. On the other hand, the channel P communicates with the chamber 0, via at least one radial orifice R, said chamber being constantly in relation to the return F, through the passage MJ.

La chambre d'évacuation 0 est également délimitée par un obturateur cylindrique 21 constitué par un bossage circulaire que présente la tige 20 au voisinage de sa portion externe et comportant une gorge périphérique 21a dans laquelle est logé un joint d'étanchéité annulaire 22.The evacuation chamber 0 is also delimited by a cylindrical obturator 21 constituted by a circular boss presented by the rod 20 in the vicinity of its external portion and comprising a peripheral groove 21a in which is housed an annular seal 22.

En position de repos, l'obturateur cylindrique 21 se trouve en appui contre une rondelle d'arrêt 23a immobilisée par un circlips 23 installé dans une gorge circulaire ménagée à l'entrée de la chemise 16 d'où émerge l'extrémité externe 24 formant gâchette de la tige 20. Cette dernière est soumise à l'action d'un ressort de compression 25 placé en appui, par ses extrémités opposées, d'une part, contre le fond d'un logement borgne 26 ménagé dans le fond de ladite tige et, d'autre part, contre le fond d'un bouchon 27 vissé dans l'extrémité taraudée de l'évidement 14 opposée à l'extrémité d'où émerge la gâchette 24, ledit ressort tendant à repousser cette dernière en position émergente.In the rest position, the cylindrical shutter 21 is in abutment against a stop washer 23a immobilized by a circlip 23 installed in a circular groove formed at the inlet of the jacket 16 from which the external end 24 forming trigger of the rod 20. The latter is subjected to the action of a compression spring 25 placed in abutment, by its opposite ends, on the one hand, against the bottom of a blind housing 26 formed in the bottom of said rod and, on the other hand, against the bottom of a plug 27 screwed into the threaded end of the recess 14 opposite the end from which the trigger 24 emerges, said spring tending to push the latter into the emerging position .

Sur la partie postérieure du boîtier arrière 1b, est articulé le levier de manoeuvre 28 du sécateur, prenant appui contre la gâchette 24 et dont le pivotement vers l'intérieur permet de repousser cette dernière à l'encontre de l'action antagoniste exercée par le ressort 25.On the rear part of the rear housing 1b, the operating lever 28 of the pruner is articulated, bearing against the trigger 24 and whose pivoting inwards makes it possible to repel the latter against the antagonistic action exerted by the spring 25.

On comprend aisément le fonctionnement de ce sécateur. Par l'intermédiaire de la valve 12 et à l'aide de tout matériel adéquat (compresseur, bouteille de gaz comprimé, pompe à main, etc.), un fluide compressible est introduit et comprimé dans les chambres coaxiales C et B, ce qui a pour effet de repousser le piston 9 vers l'arrière et de le maintenir calé contre l'épaulement 1e. Le fluide compressible utilisable est avantageusement un fluide gazeux, par exemple de l'air comprimé ou, de préférence, un gaz neutre comprimé ne se dissolvant pas ou peu dans l'huile tel qu'azote, argon, etc.We easily understand the operation of this pruning shears. Via the valve 12 and using any suitable equipment (compressor, compressed gas cylinder, hand pump, etc.), a compressible fluid is introduced and compressed in the coaxial chambers C and B, which has the effect of pushing the piston 9 backwards and keeping it wedged against the shoulder 1e. The compressible fluid which can be used is advantageously a gaseous fluid, for example compressed air or, preferably, a compressed neutral gas which does not dissolve little or not in oil such as nitrogen, argon, etc.

En position de repos correspondant à l'ouverture des lames (figures 1 à 4 et 8), l'arrivée E du fluide hydraulique communique avec le retour F, par l'intermédiaire du passage I-K-N-L-J (fonctionnement en circuit hydraulique à centre ouvert). Le fluide hydraulique tel qu'huile, remplit également le canal G et la chambre A qui, dans cette situation, présente son volume minimum, en raison de la position reculée du piston 9.In the rest position corresponding to the opening of the blades (FIGS. 1 to 4 and 8), the inlet E of the hydraulic fluid communicates with the return F, via the passage I-K-N-L-J (operation in an open center hydraulic circuit). Hydraulic fluid such as oil also fills the channel G and the chamber A which, in this situation, has its minimum volume, due to the retracted position of the piston 9.

Lorsqu'on repousse l'organe mobile 17-18-20-21 du distributeur, au moyen de levier 28 agissant sur la gâchette 24, la nouvelle position du tiroir de distribution 17 dudit organe mobile empêche la circulation de l'huile à travers les trous radiaux L et interrompt donc la communication entre l'arrivée et le retour. La pression de l'huile s'exerçant contre la face de travail du piston 9 étant alors plus importante que celle du gaz comprimé renfermé dans les chambres B et C et s'appliquant sur la face opposée dudit piston, ce dernier est repoussé vers l'avant (figures 5 et 6), ce qui entraîne le pivotement et la fermeture des lames. On observe que, dans cette position, la pression de l'huile ne s'applique pas sur les joints 19 et 22 qui équipent l'organe mobile du distributeur. En effet, l'étanchéité entre : - d'une part, les surfaces cylindriques des portions du piston d'équilibre 18 et de l'obturateur 21 disposées du côté intérieur des joints 19 et 22, respectivement, et, - d'autre part, l'alésage de la chemise 16, et principalement obtenue par la qualité des ajustements des surfaces cylindriques en contact, de sorte que lesdits joints ne supportent aucune pression. Toutefois, s'il se produit une fuite d'huile autour du piston d'équilibre 18, cette huile est collectée dans la gorge 18b et, par l'intermédiaire du passage Q-P-R-0-M-J, elle est acheminée jusqu'au retour F. Le joint 19 équipant le piston d'équilibre ne supporte donc aucune pression. D'autre part, le joint 22 dont est muni l'obturateur cylindrique 21 n'est quant à lui, soumis à aucune pression, car la chambre 0 délimitée par ledit obturateur communique en permanence avec le retour. Il est donc possible d'utiliser des pressions très importantes, compte tenu du fait que les joints ne subissent aucune déformation, quelle que soit la position de l'organe mobile du distributeur. Lorsqu'on relâche le levier 28, l'organe mobile du distributeur est repoussé par le ressort 25. de sorte que le tiroir de distribution 17 occupe une position permettant le passage de l'huile à travers les trous radiaux L, ce qui rétablit la communication entre l'arrivée E et le retour F. La pression baisse dans la chambre A et devient inférieure à celle qui est présente dans les chambres B et C. de sorte que le piston 9 se trouve repoussé vers l'arrière par la détente du gaz comprimé contenu dans ces dernières et précédemment soumis à une compression complémentaire lors du déplacement vers l'avant dudit piston, ce qui entraîne le pivotement et la réouverture des lames. La vitesse de recul du piston et donc la vitesse du pivotement des lames en position d'ouverture, sont liées à la valeur de la compression du gaz comprimé renfermé dans les chambres B et C. On comprend que, par le choix du taux de compression de ce gaz, il est possible de régler aisément et commodément la vitesse de la réouverture des lames.When the movable member 17-18-20-21 of the distributor is pushed back, by means of lever 28 acting on the trigger 24, the new position of the distribution slide 17 of said movable member prevents the circulation of oil through the radial holes L and therefore interrupts communication between arrival and return. The pressure of the oil exerted against the working face of the piston 9 then being greater than that of the compressed gas contained in the chambers B and C and applying to the opposite face of the said piston, the latter is pushed back towards the 'before (Figures 5 and 6), which causes the pivoting and closing of the blades. It is observed that, in this position, the oil pressure does not apply to the seals 19 and 22 which equip the movable member of the distributor. Indeed, the seal between: - on the one hand, the cylindrical surfaces of the portions of the balance piston 18 and of the shutter 21 disposed on the inner side of the seals 19 and 22, respectively, and, - on the other hand , the bore of the jacket 16, and mainly obtained by the quality of the adjustments of the cylindrical surfaces in contact, so that said seals do not withstand any pressure. However, if an oil leak occurs around the balance piston 18, this oil is collected in the groove 18b and, via the passage QPR-0-MJ, it is conveyed until the return F The seal 19 fitted to the balance piston therefore does not withstand any pressure. On the other hand, the seal 22 which is fitted with the cylindrical shutter 21 is not subjected to any pressure, since the chamber 0 delimited by said shutter communicates permanently with the return. It is therefore possible to use very high pressures, taking into account that the seals do not undergo any deformation, whatever the position of the movable member of the dispenser. When the lever 28 is released, the movable member of the distributor is pushed back by the spring 25. so that the distribution slide 17 occupies a position allowing the passage of the oil through the radial holes L, which restores the communication between inlet E and return F. The pressure drops in chamber A and becomes lower than that which is present in chambers B and C. so that the piston 9 is pushed back by the trigger of the compressed gas contained therein and previously subjected to additional compression during the forward movement of said piston, which causes the blades to pivot and reopen. The recoil speed of the piston and therefore the speed of pivoting of the blades in the open position are linked to the value of the compression of the compressed gas contained in chambers B and C. It is understood that, by the choice of the compression ratio of this gas, it is possible to easily and conveniently adjust the speed of the reopening of the blades.

On a illustré, à la figure 7, un agencement très avantageux de la tête de coupe du sécateur. Selon ce mode d'exécution, une butée à bille 29a, 29b est installée sur l'axe 3, de chaque côté du couple de lames 4a, 4b, entre les branches 2a, 2b de la chape constituant la portion antérieure du porte-lames 2. L'axe 3 est constitué par un boulon permettant de maintenir les lames 4a, 4b en contact l'une avec l'autre. Afin que la pression tendant à plaquer lesdites lames l'une contre l'autre soit toujours suffisante pour obtenir une coupe nette, sans toutefois contrarier le pivotement de la ou des lames mobiles, cette pression est appliquée au couple de lames par l'intermédiaire d'un organe élastique. De manière avantageuse et préférée, cet organe élastique est constitué par une rondelle Belleville 30, par exemple interposée entre la face interne de l'écrou 3a du boulon 3 et une bague 59 montée avec une aptitude de translation axiale sur la tige dudit boulon, dans un logement 2b' de l'une des branches (branche 2b) du porte-lames, cette bague mobile étant elle-même interposée entre ladite rondelle Belleville et l'une des butées à billes (butée à billes 29b).FIG. 7 illustrates a very advantageous arrangement of the cutting head of the pruning shears. According to this embodiment, a ball stop 29a, 29b is installed on the axis 3, on each side of the pair of blades 4a, 4b, between the branches 2a, 2b of the yoke constituting the front portion of the blade holder 2. The axis 3 is constituted by a bolt making it possible to keep the blades 4a, 4b in contact with one another. So that the pressure tending to press said blades against each other is always sufficient to obtain a clean cut, without however counteracting the pivoting of the movable blade or blades, this pressure is applied to the pair of blades by means of 'an elastic organ. Advantageously and preferably, this elastic member is constituted by a Belleville washer 30, for example interposed between the internal face of the nut 3a of the bolt 3 and a ring 59 mounted with an ability of axial translation on the rod of said bolt, in a housing 2b ′ of one of the branches (branch 2b) of the blade holder, this movable ring being itself interposed between said Belleville washer and one of the ball thrust bearings (ball thrust 29b).

Les figures 9 à 13 illustrent un second exemple de mise en oeuvre de l'invention appliquée à la réalisation d'un autre type'de sécateur hydraulique convenant aux travaux classiques de taille et de récolte en arboriculture, viticulture et horticulture. Ce sécateur comprend un corps évidé 31 dont la portion arrière est conformée pour servir de poignée et sur la partie antérieure duquel est installée une tête de coupe comportant un porte-lames 32 sur lequel est fixé un crochet ou lame fixe 33. Sur ce crochet, est articulée, au moyen d'un axe 34, la lame mobile 35 de ladite tête de coupe. Cette lame mobile comporte un prolongement ou levier 35a présentant une fente ouverte 36 traversée par un coulisseau d'entraînement 37 porté par l'extrémité antérieure en forme de chape 58a d'un bouchon 58 installé de manière étanche dans l'extrémité avant d'une tige alésée 38. Lors des pivotements de la lame mobile 35, le coulisseau d'entraînement 37 glisse dans la fente 36. Cette disposition facilite la liaison de la lame mobile et ae la tige. en supprimant l'emploi d'un organe intermédiaire. Sur l'extrémité postérieure cylindrique 38b de diamètre plus réduit de la tige 38, est calé un piston d'entraînement 39 muni de joints annulaires périphériques d'étanchéité et logé, avec une aptitude de coulissement étanche, dans un alésage de la portion avant du corps 31. La face de travail de ce piston délimite une chambre a de volume variable, tandis que sa face opposée délimite une chambre annulaire de volume variable b entourant la tige 38. Cette dernière peut coulisser, de manière étanche, dans un guide 40 fixé, de préférence de façon démontable, dans la partie avant de l'évidement du corps 31, ce guide étant pourvu, intérieurement et extérieurement, de joints annulaires d'étanchéité.Figures 9 to 13 illustrate a second example of implementation of the invention applied to the production of another type of hydraulic pruner suitable for conventional pruning and harvesting work in arboriculture, viticulture and horticulture. This pruner includes a hollow body 31, the rear portion of which is shaped to serve as a handle and on the front part of which is installed a cutting head comprising a blade holder 32 on which is fixed a hook or fixed blade 33. On this hook, is articulated, by means of an axis 34, the movable blade 35 of said cutting head. This movable blade has an extension or lever 35a having an open slot 36 crossed by a driving slide 37 carried by the front end in the form of a yoke 58a of a plug 58 installed in leaktight manner in the front end of a reamed rod 38. During the pivoting of the movable blade 35, the drive slide 37 slides in the slot 36. This arrangement facilitates the connection of the movable blade and the rod. by eliminating the use of an intermediate organ. On the posterior end cylindrical 38b with a smaller diameter of the rod 38, is wedged a drive piston 39 provided with peripheral annular seals and housed, with a sealing sliding capacity, in a bore of the front portion of the body 31. The face of work of this piston delimits a chamber a of variable volume, while its opposite face delimits an annular chamber of variable volume b surrounding the rod 38. The latter can slide, in a sealed manner, in a guide 40 fixed, preferably so removable, in the front part of the recess of the body 31, this guide being provided, internally and externally, with annular seals.

Dans l'alésage de la tige 38, est logé un piston libre 41 équipé de joints annulaires périphériques d'étanchéité. Ce piston libre délimite, à l'intérieur dudit alésage, d'une part, par sa face avant, une chambre c et, d'autre part, par sa face arrière, une seconde chambre d laquelle communique constamment avec la chambre annulaire b, par l'intermédiaire d'au moins un orifice e ménagé dans la paroi cylindrique de la tige 38. Les chambres concentriques b et d constituent, avec l'orifice e les faisant communiquer, une enceinte à capacité variable destinée à contenir un fluide incompressible de tranmission, comme on l'explique ci-après.In the bore of the rod 38, is housed a free piston 41 fitted with peripheral annular seals. This free piston delimits, inside said bore, on the one hand, by its front face, a chamber c and, on the other hand, by its rear face, a second chamber from which constantly communicates with the annular chamber b, by means of at least one orifice e formed in the cylindrical wall of the rod 38. The concentric chambers b and d constitute, with the orifice e making them communicate, a chamber with variable capacity intended to contain an incompressible fluid of transmission, as explained below.

Une valve 42 est installée à l'avant de la tige 38, dans un évidement axial du bouchon 58, à l'entrée de la chambre c, cette valve permettant d'introduire un fluide compressible tel qu'air, azote, argon, etc., dans ladite chambre rendue étanche au moyen dudit bouchon.A valve 42 is installed at the front of the rod 38, in an axial recess of the plug 58, at the entrance to the chamber c, this valve making it possible to introduce a compressible fluid such as air, nitrogen, argon, etc. ., in said chamber sealed by means of said plug.

L'extrémité postérieure de la tige 38 comporte en alésage axial f disposé en alignement avec un orifice axial g ménagé dans le piston 39 et communiquant avec la chambre a. Dans l'alésage f, est logé un clapet anti-retour 43 et un ressort de compression 44 tendant à maintenir ledit clapet contre le bord avant de l'orifice g. Dans l'alésage f, débouchent deux perçages radiaux h s'ouvrant dans la surface latérale d'une portion tronconique 38c que présente la tige 38 en avant de son extrémité postérieure cylindrique de diamètre réduit engagée dans le piston 39, c'est-à-dire à proximité immédiate et en avant de ce dernier. Cette surface conique sert de siège à un clapet annulaire 45 présentant une surface d'appui conique complémentaire. Ce clapet 45 est pourvu de rainures périphériques 45a orientées parallèlement à son axe, et il est maintenu sur son siège par un moyen élastique avantageusement constitué par une rondelle Belleville 46 interposée entre sa face postérieure et la face avant du piston 39.The rear end of the rod 38 has an axial bore f arranged in alignment with an axial orifice g formed in the piston 39 and communicating with the chamber a. In the bore f, is housed a non-return valve 43 and a compression spring 44 tending to hold said valve against the front edge of the orifice g. In the bore f, open two radial holes h opening in the lateral surface of a frustoconical portion 38c which has the rod 38 in front of its cylindrical rear end of reduced diameter engaged in the piston 39, that is to say - say in the immediate vicinity and in front of the latter. This conical surface serves as a seat for an annular valve 45 having a complementary conical bearing surface. This valve 45 is provided with peripheral grooves 45a oriented parallel to its axis, and it is held on its seat by an elastic means advantageously constituted by a Belleville washer 46 interposed between its rear face and the front face of the piston 39.

A l'extrémité avant de la chambre annulaire b, est positionnée fixement une bague de butée 47 ayant une double foncion : - d'une part. limiter la course du piston 39 vers l'avant et. - d'autre part. soulever le clapet 45 de son siège lorsque ledit piston arrive en fin de course d'avancement.At the front end of the annular chamber b, is fixedly positioned a stop ring 47 having a double function: - on the one hand. limit the stroke of piston 39 towards the front and. - on the other hand. lift the valve 45 from its seat when said piston reaches the end of the travel stroke.

Un orifice de purge 48 communiquant avec l'extrémité antérieure de la chambre annulaire b. est prévu dans le corps 31, cet orifice étant équipé d'un organe d'obturation étanche.A purge orifice 48 communicating with the anterior end of the annular chamber b. is provided in the body 31, this orifice being equipped with a sealed closure member.

Le distributeur hydraulique est installé dans un évidement borgne transversal 49 ménagé dans la partie arrière du corps 31. Un conduit i, constitué par un perçage longitudinal exécuté dans la partie arrière du corps, établit une communication entre la chambre a délimitée par la face de travail du piston d'entraînement 39 et l'évidement transversal borgne 49 dans lequel débouchent encore :

  • d'une part, l'orifice d'alimentation ou arrivée j du fluide hydraulique sous pression ;
  • d'autre part, l'orifice de retour k.
The hydraulic distributor is installed in a transverse blind recess 49 formed in the rear part of the body 31. A conduit i, constituted by a longitudinal drilling executed in the rear part of the body, establishes a communication between the chamber delimited by the working face of the drive piston 39 and the blind transverse recess 49 into which still open:
  • on the one hand, the supply or inlet port j of the hydraulic fluid under pressure;
  • on the other hand, the return port k.

Suivant l'exemple illustré, l'extrémité postérieure du corps 31 est agencée pour recevoir un dispositif (non représenté) permettant l'accouplement démontable, commode et rapide, du sécateur à des flexibles coaxiaux d'alimentation et de retour reliés à une source de fluide hydraulique sous pression, un tel dispositif d'accouplement démontable étant décrit dans le document FR-A-2419453. Le distributeur comprend une chemise cylindrique 50 installée fixement dans l'évidement 49, un organe mobile de distribution monté avec une aptitude de coulissement dans l'alésage axial de ladite chemise, et un ressort de compression 51 interposé entre le fond dudit évidement et le fond d'une cavité axiale ménagée dans la portion interne dudit organe.According to the example illustrated, the rear end of the body 31 is arranged to receive a device (not shown) allowing the demountable, convenient and rapid coupling of the pruning shears to coaxial supply and return hoses connected to a source of hydraulic fluid under pressure, such a removable coupling device being described in document FR-A-2419453. The distributor comprises a cylindrical jacket 50 fixedly installed in the recess 49, a mobile distribution member mounted with a sliding ability in the axial bore of said jacket, and a compression spring 51 interposed between the bottom of said recess and the bottom an axial cavity formed in the internal portion of said member.

La chemise cylindrique 50 comporte deux gorges annulaires périphériques I, m. La gorge I communique en permanence avec l'arrivée j, et également avec l'alésage q de la chemise par l'intermédiaire de trous radiaux n dont l'entrée est placée dans la partie arrière de ladite gorge, par rapport à l'extrémité externe de ladite chemise. La gorge m communique directement avec le conduit i, et aussi avec l'alésage q de la chemise, par l'intermédiaire de trous radiaux o disposés en arrière des trous n.The cylindrical jacket 50 has two peripheral annular grooves I, m. The groove I communicates permanently with the inlet j, and also with the bore q of the liner by means of radial holes n, the inlet of which is placed in the rear part of the said groove, relative to the end. external of said shirt. The groove m communicates directly with the conduit i, and also with the bore q of the jacket, by means of radial holes o arranged behind the holes n.

L'organe mobile du distributeur est avantageusement exécuté en une seule pièce et comprend un tiroir de distribution 52 délimitant, avec un piston d'équilibre 53, une chambre annulaire p laquelle est en relation constante avec l'arrivée j, par le passage n-I. Ledit organe mobile comprend encore une gâchette ou poussoir 54 constituée par l'une de ses extrémités émergeant de l'entrée de la chemise, et il est maintenu à l'intérieur de cette dernière au moyen d'une rondelle d'arrêt 55 immobilisée par un circlips 56 positionné dans une rainure circulaire interne ménagée à proximité de l'entrée de ladite chemise et contre laquelle s'appuie la face externe du piston d'équilibre, sous la poussée du ressort 51.The movable member of the dispenser is advantageously executed in a single piece and comprises a dispensing slide 52 defining, with a balance piston 53, an annular chamber p which is in constant relation with the inlet j, through the passage n-I. Said movable member also comprises a trigger or pusher 54 constituted by one of its ends emerging from the inlet of the liner, and it is held inside the latter by means of a stop washer 55 immobilized by a circlip 56 positioned in an internal circular groove formed near the inlet of said jacket and against which the external face of the balance piston bears, under the thrust of the spring 51.

Le montage du distributeur hydraulique dans un alésage borgne et le maintien de l'organe mobile dudit distributeur au moyen d'un circlips positionné à l'entrée de la chemise fixe de ce dernier, permettent d'obtenir une très bonne étanchéité et facilitent grandement l'execution du logement dudit distributeur et la mise en place de ses organes constitutifs.The mounting of the hydraulic distributor in a blind bore and the maintenance of the movable member of said distributor by means of a circlip positioned at the entrance of the fixed jacket of the latter, make it possible to obtain a very good seal and greatly facilitate the 'execution of the housing of said distributor and the establishment of its constituent bodies.

Sur la partie postérieure du corps 31, est articulé le levier de manoeuvre 57 du sécateur prenant appui contre l'extremite externe de la gâchette 54.On the rear part of the body 31 is articulated the operating lever 57 of the pruning shears bearing against the external end of the trigger 54.

On décrit ci-après le mode d'utilisation et le fonctionnement du sécateur qui vient d'être décrit.The mode of use and operation of the pruning shears which have just been described are described below.

Le sécateur est d'abord préparé pour pouvoir fonctionner. Dans ce but, la chambre c est remplie d'un fluide gazeux comprimé, par l'intermédiaire de la valve 42 et à l'aide de tout matériel adéquat, ce qui a pour effet de maintenir ou de repousser le piston libre 41 dans le fond de l'alésage de la tige de piston 38, l'orifice de purge 48 étant ouvert pour l'évacuation de l'air se trouvant dans la chambre d. Le sécateur étant branché à la source de fluide hydraulique sous pression, le fluide hydraulique sous pression tel qu'huile est ensuite envoyé, en agissant sur le distributeur, contre la face de travail du piston d'entraînement 39 qui se trouve repoussé vers l'avant en même temps que la tige 38 et le clapet 45 disposé à l'avant dudit piston. En fin de course, la butée 47 provoque le soulèvement du clapet 45. Compte tenu de l'ouverture des perçages radiaux h, le clapet anti-retour 43 est décollé de son siège et l'huile pénètre dans les chambres b et d qui présentent leur volume minimum. Ces chambres se remplissent d'huile laquelle chasse l'air qui s'y trouve. Lorsque l'huile sort de l'orifice de purge 48, ce dernier est obturé à l'aide de son obturateur étanche. La pression qui est alors créée dans les chambres b et d a pour effet de repousser le piston libre 41 vers l'avant, en augmentant le volume de la chambre d et en soumettant le gaz comprimé renfermé dans la chambre c dont le volume diminue, à une compression supplémentaire. Lorsque cette compression s'équilibre avec la pression du fluide hydraulique sous pression, le piston libre s'immobilise et le clapet 43 obture l'orifice g d'entrée dudit fluide hydraulique dans l'enceinte constituée par les chambres b et d, et l'orifice e faisant communiquer ces dernières.The pruning shears are first prepared to work. For this purpose, the chamber c is filled with a compressed gaseous fluid, via the valve 42 and with the aid of any suitable material, which has the effect of maintaining or pushing the free piston 41 in the bottom of the bore of the piston rod 38, the bleed orifice 48 being open for the evacuation of the air located in the chamber d. The pruning shears being connected to the source of pressurized hydraulic fluid, the pressurized hydraulic fluid such as oil is then sent, by acting on the distributor, against the working face of the drive piston 39 which is pushed towards the before at the same time as the rod 38 and the valve 45 disposed at the front of said piston. At the end of the race, the stop 47 causes the valve 45 to be raised. Given the opening of the radial bores h, the non-return valve 43 is detached from its seat and the oil enters the chambers b and d which have their minimum volume. These chambers are filled with oil which expels the air therein. When the oil comes out of the bleed orifice 48, the latter is closed using its sealed shutter. The pressure which is then created in the chambers b and da has the effect of pushing the free piston 41 forwards, by increasing the volume of the chamber d and by subjecting the compressed gas contained in the chamber c, the volume of which decreases, to additional compression. When this compression is balanced with the pressure of the hydraulic fluid under pressure, the free piston comes to a standstill and the valve 43 closes the orifice g for entry of said hydraulic fluid into the enclosure constituted by chambers b and d, and l orifice making these communicate.

Le sécateur est alors prêt à fonctionner et, comme on le décrit en détail ci-après, en relâchant le levier de manoeuvre 57, on obtient le retour vers l'arrière des deux pistons et l'ouverture des lames. En position de repos correspondant à l'ouverture des lames (figures 9 à 11), le fluide hydraulique sous pression provenant de l'arrivée j, remplit la chambre annulaire p, par l'intermédiaire du passage n-I. mais la position du tiroir de distribution 52 interdit toute communication :

  • d'une part, avec la chambre a délimitée par la face de travail du piston d'entraînement 39 ;
  • d'autre part, avec le retour k (fonctionnement en circuit hydraulique à centre fermé).
The pruning shears are then ready to operate and, as described in detail below, by releasing the operating lever 57, the two pistons return to the rear and the blades open. In the rest position corresponding to the opening of the blades (Figures 9 to 11), the pressurized hydraulic fluid from the inlet j, fills the annular chamber p, via the passage nI. but the position of the distribution drawer 52 prevents any communication:
  • on the one hand, with the chamber delimited by the working face of the drive piston 39;
  • on the other hand, with the return k (operation in a closed center hydraulic circuit).

En outre, la chambre a communique avec le retour par le passage i-m-o-q et le fond de l'évidement 49.In addition, the chamber a communicates with the return by the passage i-m-o-q and the bottom of the recess 49.

Lorsqu'on repousse l'organe mobile 52-53-54 du distributeur, au moyen du levier 57 appuyant sur la gâchette 54, à l'encontre de l'action antagoniste du ressort 51, la nouvelle position du tiroir ce distribution 52 :

  • permet l'arrivée de l'huile sous pression dans la chambre a par le passage I-n-p-o-m-i ;
  • interrompt la communication entre la chambre a et le retour k. L'arrivée de l'huile sous pression dans la chambre a provoque le déplacement vers l'avant du piston d'entraînement 39 et de la tige de piston 38, ce qui entraîne le pivotement de la lame mobile 35 dans la position de fermeture des lames correspondant à l'action de coupe du sécateur (figures 12 et 13). Le déplacement du piston d'entraînement vers l'avant a pour conséquence d'appliquer une pression sur l'huile contenue dans les chambres b et d communiquant par l'intermédiaire de l'orifice e, lesdites chambres présentant, avant ce déplacement, leurs volumes maximum et minimum, respectivement. Cette pression est répercutée sur la face arrière du piston libre 41 qui se trouve repoussé vers l'avant en appliquant une compression supplémentaire au gaz compressible et comprimé renfermé dans la chambre c.
When the movable member 52-53-54 of the distributor is pushed back, by means of the lever 57 pressing the trigger 54, against the antagonistic action of the spring 51, the new position of the drawer this distribution 52:
  • allows the pressurized oil to enter the chamber a through the Inpomi passage;
  • interrupts the communication between room a and return k. The arrival of the pressurized oil in the chamber a causes the displacement piston 39 and the piston rod 38 to move forward, which causes the movable blade 35 to pivot in the closed position of the blades corresponding to the cutting action of the pruning shears (Figures 12 and 13). The displacement of the drive piston forwards has the effect of applying pressure to the oil contained in the chambers b and d communicating via the orifice e, said chambers having, before this displacement, their maximum and minimum volumes, respectively. This pressure is reflected on the rear face of the free piston 41 which is pushed forward by applying additional compression to the compressible and compressed gas contained in the chamber c.

Comme indiqué précédemment, le clapet 45 est soulevé de son siège, à l'encontre de l'action antagoniste de la rondelle Belleville 46, lorsqu'il rencontre la butée 47. De la sorte, les très légères fuites d'huile inévitables dans tout système de vérin sont automatiquement compensées par l'entrée, dans les chambres b et d, d'une quantité correspondante d'huile provenant de la chambre a, à travers le passage g-f-h. En effet, quand le volume d'huile contenu dans les chambres b et d diminue, la pression s'exerçant sur la face postérieure du clapet anti-retour 43 permet de le décoller de son siège lorsque le clapet 45 est soulevé du sien, ce qui autorise l'entrée d'une quantité compensatrice d'huile dans lesdites chambres, jusqu'à ce que les pressions s'équilibrent dans lesdites chambres et dans la chambre c. De la sorte, le volume d'huile contenu dans les chambre b et d est toujours constant.As indicated previously, the valve 45 is raised from its seat, against the antagonistic action of the Belleville washer 46, when it meets the stop 47. In this way, very slight oil leaks inevitable in all cylinder system are automatically compensated by the entry into chambers b and d of a corresponding amount of oil from chamber a through the passage gfh. Indeed, when the volume of oil contained in the chambers b and d decreases, the pressure exerted on the rear face of the non-return valve 43 makes it possible to take it off from its seat when the valve 45 is lifted from its own, this which allows the entry of a compensating quantity of oil into said chambers, until the pressures balance in said chambers and in chamber c. In this way, the volume of oil contained in the chambers b and d is always constant.

Lorsqu'on relâche le levier 57, l'organe mobile 52-53-54 du distributeur est repoussé par le ressort 51 et le tiroir de distribution 52 revient à sa position précédente suivant laquelle :

  • il interrompt la communication entre l'arrivée j et la chambre a ;
  • il rétablit la communication entre la chambre a et le retour k, par le passage i-m-o-q et le fond de l'évidement 49. Par suite de la disparition de la pression d'arrivée sur la face de travail du piston d'entraînement 39, le gaz comprimé contenu dans le chambre c peut se décomprimer et cette décompression a pour effet de repousser le piston libre 41 vers l'arrière. En reculant, ce dernier refoule l'huile contenue dans la chambre d, cette huile passant dans la chambre annulaire b en provoquant le recul du piston 39 et de la tige 38, ce qui entraîne le pivotement de la lame mobile 35 dans la position d'ouverture (figure 9 à 11). On a représenté, aux figures 14 à 16 un autre mode d'exécution de l'outil de coupe proprement dit d'un sécateur de type analogue à celui qui est illustré aux figures 1 à 8.
When the lever 57 is released, the movable member 52-53-54 of the dispenser is pushed back by the spring 51 and the dispensing drawer 52 returns to its previous position according to which:
  • it interrupts the communication between arrival j and room a;
  • it re-establishes the communication between the chamber a and the return k, through the passage imoq and the bottom of the recess 49. As a result of the disappearance of the inlet pressure on the working face of the drive piston 39, the compressed gas contained in the chamber c can decompress and this decompression has the effect of pushing the free piston 41 backwards. By moving back, the latter pushes back the oil contained in the chamber d, this oil passing through the annular chamber b causing the piston 39 and the rod 38 to retreat, which causes the movable blade 35 to pivot in the position d opening (figure 9 to 11). FIGS. 14 to 16 show another embodiment of the cutting tool proper of a pruner of the type similar to that which is illustrated in FIGS. 1 to 8.

Pour cette raison, les organes de cet outil de coupe identiques ou remplissant les mêmes fonctions que ceux de l'outil de coupe du sécateur illustré aux figures 1. 2. 3 et 5, sont désignés par les mêmes références. D'autre part, dans un but de concision, le distributeur hydraulique logé dans la poignée de manceuvre, le tuyau de jonction et le tube allongé reliant, respectivement, ledit distributeur et ladite poignée, à l'outil de coupe, ne sont pas représentés.For this reason, the members of this cutting tool identical or fulfilling the same functions as those of the pruner cutting tool illustrated in Figures 1. 2. 3 and 5, are designated by the same references. On the other hand, for the sake of brevity, the hydraulic distributor housed in the maneuvering handle, the junction pipe and the elongated tube connecting, respectively, said distributor and said handle, to the cutting tool, are not shown. .

Ce mode d'exécution simplifié et économique diffère de celui qui est illustré aux figures 1 à 8, principalement par le fait que la chambre de rappel B renfermant ou apte à renfermer le fluide gazeux comprimé, est délimitée par la grande face du piston d'entraînement 9 et est disposée dans la partie arrière du boîtier avant 1a, tandis que la chambre hydraulique de pression A est délimitée par la petite face de travail dudit piston et disposée autour de la tige 8, dans la partie avant dudit boîtier. La valve 12 permettant d'introduire le fluide gazeux comprimé dans la chambre de rappel B est donc installée dans un logement ménagé dans la partie arrière du boîtier 1a et débouchant dans ladite chambre, tandis que l'orifice H' d'entrée du fluide hydraulique dans la chambre de pression A est exécutée dans la partie avant dudit boîtier.This simplified and economical embodiment differs from that illustrated in FIGS. 1 to 8, mainly by the fact that the return chamber B containing or capable of enclosing the compressed gaseous fluid, is delimited by the large face of the piston. drive 9 and is arranged in the rear part of the front housing 1a, while the hydraulic pressure chamber A is delimited by the small working face of said piston and disposed around the rod 8, in the front part of said housing. The valve 12 making it possible to introduce the compressed gaseous fluid into the return chamber B is therefore installed in a housing provided in the rear part of the housing 1a and opening into said chamber, while the orifice H ′ of inlet of the hydraulic fluid in the pressure chamber A is executed in the front part of said housing.

Grâce à une telle construction, on obtient une meilleure étanchéité au fluide gazeux comprimé contenu dans la chambre de rappel B laquelle est obturée, de manière étanche, dans sa partie arrière, au moyen de la valve 12.Thanks to such a construction, a better seal is obtained against the compressed gaseous fluid contained in the return chamber B which is sealed in its rear part by means of the valve 12.

Claims (16)

1. Portable hydraulic tool, for example hydraulic secateurs for operations of cutting or harvesting in agriculture, arboriculture, viticulture or horticulture, having a single acting ram comprising : a driving piston (9, 39) disposed with a possibility of fluid tight sliding in the bore of a hollowed body (1, 31) and the active stroke of which takes place under the thrust of a hydraulic fluid under pressure acting on the working face of the said piston, a piston rod (8, 38) connected to at least one movable member (4a, 4b ; 35) of the said tools, and a return chamber (B, c) of variable volume and the volume of which decreases when the driving piston is displaced under the thrust of the hydraulic fluid under pressure, characterised i.n that the said return chamber (B, c) is fluid tight or equipped with a fluid tight closure means (10, 12, 52-48) and encloses or is adapted to enclose a compressed compressible fluid, preferably a compressed gaseous fluid, such that when the driving piston (9, 39) is displaced under the thrust of the hydraulic fluid under pressure, the expansion of this compressed gaseous fluid automatically causes the return of the said piston, when the thrust exerted by the said hydraulic fluid on the working face of this latter becomes less than that of the said compressed gaseous fluid.
2. Portable hydraulic tool, according to claim 1, characterised in that the return chamber (B) is disposed about the piston rod (8), forming an annular return chamber.
3. Portable hydraulic tool according to claim 2 characterised in that a reservoir chamber (C) is provided at the interior of the piston rod (8), this chamber communicating with the annular return chamber (B), for example by means of at least one radial hole (D).
4. Portable hydraulic tool according to claim 1 characterised in that the return chamber (B) is bounded by the large face of the driving piston (9) whilst the hydraulic pressure chamber (A) is disposed about the rod (8) of the said piston and is bounded by the small working face of this latter.
5. Portable hydraulic tool according to claim 1 characterised in that it comprises a fluid tight enclosure (b, d, e) enclosing or adapted to enclose a constant volume of an incompressible transmission fluid such as, for example, oil, this enclosure being bounded on the one hand by the face of the driving piston (39) opposite to its working face on which is applied the thrust of the hydraulic fluid coming from the source of fluid under pressure and, on the other hand, by one of the faces of a free piston (41) bounding, by its opposite face, the return chamber (c) containing the compressed compressible fluid and constituted by the bore in which can slide, in fluid tight manner, the said free piston.
6. Portable hydraulic tool, according to claim 5, characterised in that the return chamber (c) bounded by one of the faces of the free piston (41) is constituted by a bore of the rod (38) of the driving piston (39), whilst the fluid tight enclosure enclosing or adapted to enclose the incompressible transmission fluid comprises : an annular chamber (b) provided about the rod (38) a chamber (d) bounded by the opposite face of the said free piston and by the bore of the said rod in which this latter moves, and at least one orifice (e) establishing a constant communication between the said chambers (b, d).
7. Portable hydraulic tool according to any one of claims 4 to 6 characterised in that it comprises means permitting the automatic introduction, in the course of operation of the said tools, of compensating quantities of transmission fluid into the enclosure enclosing the incompressible transmission fluid, when the volume of this latter diminishes in the said enclosure.
8. Portable hydraulic tool, according to claim 7 and one of claims 5 or 6, characterised in that the means permitting the automatic introduction of compensating quantities of transmission fluid comprise an orifice (g) provided in the driving piston (39) and serving as a seat for a non-return valve (43) subjected to the action of a compression spring (44) tending to press it on its seat and installed in a bore (f) formed in the rear end of the driving rod (38), the said bore communicating with radial openings (h) opening in the lateral surface of a frusto-conical portion (38c) of the said rod (38) in proximity to and in front of the said driving piston (39), this conical surface serving as a seating for an annular valve (45) having a complementary conical bearing surface, this annular valve being maintained on its seat by a resilient means constituted, preferably, by a Belleville washer (46) interposed between its rear face and the forward face of the driving piston (39). a stop (47) being disposed fixedly at the forward end of the annular chamber (b) in order to lift the annular valve (45) from its seat, when the said driving piston arrives at the end of its advancing stroke.
9. Portable hydraulic tool according to one of claims 7 or 8 characterised in that it comprises a purging orifice (48) provided with a fluid tight closure, the said orifice opening into the enclosure (b) containing the incompressible transmission fluid, preferably at the forward end of this latter.
10. Portable hydraulic tools, according to claim 1, such as hydraulic secateurs for operations of cutting or harvesting in agriculture, arboriculture, viticulture or horticulture, comprising a body (1) at the forward part (1a) of which is installed a cutting head comprising two pivoting blades (4a, 4b) carried by an axle (3) constituted by a bolt and coupled to the rod (8) of the driving piston (9) characterised in that a ball thrust member (29a, 29b) is installed on the said axle, at each side of the pair of blades, and in that the pressure tending to press the blades one against the other is applied to these latter by means of a resilient member formed, preferably, by a Belleville washer disposed on the rod of the bolt (3) and interposed, for example, between the internal face of the nut (3a) of the said bolt and a ring (59) mounted, with a capability of axial translation, on the said rod on the bolt and placed in contact against one of the ball thrust members.
11. Portable hydraulic tool, according to claim 1, such as hydraulic secateurs for operations of cutting or harvesting in agriculture, arboriculture, viticulture or horticulture, comprising a body (31) at the forward part of which is installed a cutting head comprising two blades (33, 35) one pivoting blade (35) of which is coupled kinematically to the rod (38) of the driving piston (39), characterised in that the said pivoting blade comprises an open recess (36) traversed by a driving slide (37) carried by the front end of the said rod (38).
12. Portable hydraulic tools according to claim 1, for operation in hydraulic circuit with closed centre, comprising a single acting distributor installed in the rear part of the body (31) and comprising a fixed sleeve (50) provided with peripheral throats and radial holes for the circulation of the hydraulic fluid, and a movable distribution member (52, 53, 54) disposed, with a capability of sliding in the said sleeve, characterised in that the said hydraulic distributor is installed in a blind transverse recess (49) of the said body.
13. Portable hydraulic tool according to claim 1, for operation in hydraulic circuit with open centre, provided with a single acting distributor installed in the rear part (1a) of the body (1) and comprising a fixed sleeve (16) provided with peripheral throats and radial holes for the circulation of hydraulic fluid, and a movable distribution member comprising successively a trigger portion (24), a cylindrical closure (21) provided with an annular peripheral sealing joint (22). a distribution handle (17) and a balancing piston (18) provided with an annular peripheral sealing joint (19). characterised in that the distribution handle (17) and the balancing piston (18) bound a distribution chamber (N) in constant communication with the inlet (E) of the hydraulic fluid coming from the source of hydraulic fluid and with the chamber (A) bounded by the working face of the driving piston (9). the said distribution chamber being capable of being placed, or not, in communication with the return (F) by means of the distribution handle (17), the said distribution handle bounding, with the cylindrical closure (21) an evacuation chamber (0) in constant relation with the return (F), by means of at least one radial orifice (M) formed in the said sleeve (16) ; and in that the balancing piston (18) comprises an annular peripheral throat (18b) disposed between its internal face and its annular sealing joint (19), the said throat communicating with the evacuation chamber (0) by means of an axial channel (P) provided in the said movable member of the distributor, at least one radial orifice (Q) coupling this axial channel and the said peripheral throat (18b), and at least one radial orifice (R) coupling the said axial channel and the said evacuation chamber.
14. Portable hydraulic tool according to any one of claims 1, 12 or 13, comprising a distributor installed in a transverse recess formed in the rear part of the body (1, 31) and comprising a fixed sleeve (16, 50) provided with peripheral throats and radial holes for the circulation of the hydraulic fluid, and a movable distribution member (18-17-21-24 ; 52-53-54) disposed, with a capability of sliding in the said sleeve ; characterised in that the said movable member (18-17-21-24 ; 52-53-54) is retained in the fixed sleeve (16, 50) by means of a circlip (23, 56) positioned in an internal circular groove formed near to the inlet of the said sleeve.
15. Process for the return of the piston of single acting rams of portable hydraulic tools such as for example hydraulic secateurs for operations of cutting or harvesting in agriculture, arboriculture, viticulture or horticulture, having a single acting ram comprising : a driving piston (9, 39) disposed, with a capability of sliding in fluid tight manner in the bore of a hollow body (1, 31) and the working stroke of which occurs under the thrust of a hydraulic fluid under pressure pressing on the working face of the said piston : a piston rod (8, 38) coupled kinematically to at least one movable element (4a, 4b ; 35) of the said tools and a return chamber (B, c) of variable volume and of which the volume decreases when the piston moves under the thrust of the hydraulic fluid under pressure, characterised in that the return of the said piston takes place under the thrust of a compressible fluid such as.. for example, a gaseous fluid, compressed and enclosed in the said return chamber (B. c) of variable volume. made fluid tight, the said fluid being subjected to a supplementary compression during the displacement of the said driving piston under the thrust of the hydraulic fluid under pressure coming from the source of hydraulic fluid under pressure.
16. Process according to claim 15 characterised in that the return thrust resulting from the expansion of the compressible fluid is transmitted to the driving piston (39) by means of an incompressible fluid.
EP83430037A 1982-11-22 1983-11-21 Portable hydraulic tools, e.g. hydraulic sécateurs, and process for returning their piston cylinder Expired EP0109912B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT83430037T ATE26901T1 (en) 1982-11-22 1983-11-21 PORTABLE HYDRAULIC TOOLS SUCH AS HYDRAULIC PRUNING SHEARS AND METHODS OF RETRACTING THE PISTONS FROM THEIR CYLINDERS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8219629A FR2536246A1 (en) 1982-11-22 1982-11-22 PORTABLE HYDRAULIC TOOLS, FOR EXAMPLE HYDRAULIC SECTORS, AND METHOD FOR RECALLING THE PISTON OF THEIR JACK
FR8219629 1982-11-22

Publications (2)

Publication Number Publication Date
EP0109912A1 EP0109912A1 (en) 1984-05-30
EP0109912B1 true EP0109912B1 (en) 1987-05-06

Family

ID=9279447

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83430037A Expired EP0109912B1 (en) 1982-11-22 1983-11-21 Portable hydraulic tools, e.g. hydraulic sécateurs, and process for returning their piston cylinder

Country Status (5)

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US (1) US4644648A (en)
EP (1) EP0109912B1 (en)
AT (1) ATE26901T1 (en)
DE (1) DE3371269D1 (en)
FR (1) FR2536246A1 (en)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4850111A (en) * 1987-09-29 1989-07-25 Food Industry Equipment International, Inc. Pneumatic control system for meat trimming knife
US4922613A (en) * 1987-09-29 1990-05-08 Food Industry Equipment International, Inc. Pneumatic control system for meat trimming knife
US4967474A (en) * 1990-03-26 1990-11-06 Wells Andrew J Hand-held power-operated shears
FR2677908B1 (en) * 1991-06-20 1995-04-07 Hydr Am VERSATILE SELF-CONTAINED TOOL SUCH AS SHEARS / HYDRAULICALLY CONTROLLED SPREADERS.
ES2120366B1 (en) * 1996-06-13 1999-05-01 Tecnologico Robotiker Centro ROBOTIC DISASSEMBLY PROCEDURE OF ELECTRICAL DEVICES AND CORRESPONDING TOOL.
CN105829028B (en) * 2013-12-10 2017-11-03 株式会社泉精器制作所 Oil pressure tool
FR3028715B1 (en) * 2014-11-25 2017-03-31 Pellenc Sa MOTORIZED CUTTING TOOL GUARDED.

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2742929A (en) * 1953-03-27 1956-04-24 Gen Motors Corp Pressure storage device
US3212520A (en) * 1963-07-25 1965-10-19 Sydney E Carlton Swing type check valve with internal relief valve
US3330037A (en) * 1965-03-26 1967-07-11 Kenneth H Hoen Cutting tool
US3707984A (en) * 1971-09-02 1973-01-02 Caterpillar Tractor Co Hydraulic valve with leakage control
US3893237A (en) * 1973-08-03 1975-07-08 Donald E Jahnke Poultry cutter
FR2401604A1 (en) * 1977-09-01 1979-03-30 Lavijerie Jacques Pneumatically operated secateurs - has one blade moved by valve controlled piston and returned by spring on release of pressure

Also Published As

Publication number Publication date
FR2536246B1 (en) 1985-03-22
US4644648A (en) 1987-02-24
DE3371269D1 (en) 1987-06-11
FR2536246A1 (en) 1984-05-25
ATE26901T1 (en) 1987-05-15
EP0109912A1 (en) 1984-05-30

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